# Explain why the biomass available at each trophic level decreases as you move up a food chain.

> AQA GCSE Biology (8461) — 4.7.4 Trophic levels in an ecosystem (Bio only) · Explain · 4 marks

## Mark scheme (4 marks)

1. Not all biomass/material eaten is absorbed/converted into new biomass by the organism
2. Biomass is lost through respiration (releasing energy for movement/heat/life processes)
3. Biomass is also lost in waste products such as faeces and urine
4. Therefore less biomass is available to pass on to the next trophic level / only a small percentage of biomass is transferred between trophic levels

## Key terms

- [trophic level](https://www.gradenine.co.uk/glossary/trophic-level)
- [biomass](https://www.gradenine.co.uk/glossary/biomass)
- [food chain](https://www.gradenine.co.uk/glossary/food-chain)

## Related

- [Revision notes for AQA GCSE Biology (8461)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-the-biomass-available-at-aa707f52) · Published by Druglandscape Ltd.